Calls for a carbon tax on fossil fuels like gasoline and coal are coming from a surprising quarter these days — Republicans. In recent weeks, several prominent Republican thinkers have floated the idea of imposing higher taxes on gasoline, coal and natural gas. The increases, they say, would be offset by tax cuts on paychecks, dividends or corporate taxes. A carbon tax is considered heresy to many conservatives. The idea is to tax something society wants less of (in this case pollution) and reduce taxes on things it wants more of (in this case work). “You just change what you tax, not increase the size of the government,” said Bob Inglis, a former Republican member of Congress,